Running Mint 14/Cinnamon 1.6, and selected "Arc-Brave-Userlist" in mdmsetup for my login window (along with "Themed with face browser") - but my picture (~/.face) doesn't appear in the initial login window. Weidly though, the picture DOES appear on the unlock screen, as well as in my account details under Administration->User Accounts.

I tried coping my ~/.face file to /usr/share/faces as well as /usr/share/pixmaps, and tried renaming it from ".face" to my username, with and without an initial capital letter, and with/without the .PNG extension, but nothing seems to work. In Mint 13, placing the file into /usr/share/faces (as my username, with a capital first letter) worked...

I had the same problem. You can get it to appear there by setting the picture in the "User Accounts" program. Seems like a bug that changing or setting it in one place doesn't make it get picked up everywhere.